Introduction

Posterior urethral stenosis (PUS) is a pathological narrowing from the bladder neck to the membranous urethra. Pelvic fracture urethral injury is the most common etiology in developing countries. However, in developed countries, iatrogenic injury secondary to treatment for prostate cancer or benign prostatic hyperplasia is the primary cause. Recalcitrant PUS presents a significant clinical and technical challenge for the practicing urologist.

Epidemiology

The preponderance of PUS in the United States is attributable to prostate cancer therapy, with an incidence of approximately 5% following primary treatment.¹ Although the robotic platform has improved stricture rates following prostatectomy, vesicourethral anastomotic stricture (VUAS) still occurs. VUAS typically presents within the first 6 months after surgery, with the incidence increasing with patient age and vascular comorbidities as well as surgical factors such as postoperative urine leak and hematoma. Radiation, on the other hand, causes cell damage resulting in a fibroblast dysfunction and progressive fibrosis that culminates in bladder neck contracture (BNC), prostate urethral stenosis and bulbomembranous stricture (BMUS). Post-radiation PUS tends to present later and is more complex, especially following brachytherapy.

Clinical Evaluation

Patients typically present with either obstructive lower urinary tract symptoms or incidentally after attempted catheter placement. Evaluation usually includes retrograde urethrogram (RUG), voiding cystourethrogram (VCUG), cystoscopy and selective urodynamics to evaluate the length, location and lumen of the stenosis, and function of the lower urinary tract. Prostate specific antigen (PSA), computerized tomography (CT) and magnetic resonance imaging (MRI) may be used to evaluate for recurrent cancer, pubic osteomyelitis, prostate necrosis/calcification and bladder disease.

Surgical Decision Making

The goal of intervention is to secure safe egress for urine while maintaining continence and minimizing convalescence (fig. 1). Management begins with endoscopic dilation or incision with multiple technologies, offering good response rates when allowing for one to two procedures. Patients with failed repeat endoscopic intervention who are motivated and medically fit to proceed with major surgery are evaluated for reconstruction or diversion. Those with severe pain, necrosis, dystrophic calcification or a small capacity bladder are best managed with cystectomy and diversion.² Patients who are frail with multiple comorbid conditions are best managed with nonsurgical therapy.

Figure 1. Algorithm for management of posterior urethral stenosis. TUI, transurethral incision.

Nonsurgical Management

Patients with recurrent but nonobliterative PUS usually undergo dilation/direct vision internal urethrotomy (DVIU) followed by a regimen of chronic self-dilation. An indwelling catheter is sometimes preferred over self-dilation by patients in acute retention or those unable to perform self-catherization due to pain, fear of urethral injury or poor dexterity. Patients needing long-term drainage are best served with chronic suprapubic catheterization to avoid urethral erosion. Suprapubic catheterization and intermittent catheterization are associated with lower rates of urinary tract infection compared to indwelling urethral catheterization.

Endoscopic Management

Options for endoscopic intervention include dilation, incision and resection, with patency rates of 54% to 100% and de novo incontinence developing in 0% to 52%.³ Dilation is best performed with a guidewire placed under direct vision followed by coaxial dilators or a balloon. Transurethral incision may be performed with a cold-knife urethrotome, electrocautery via a resectoscope or Colling’s knife, or a laser. Incision should be performed laterally at the 3 and 9 o’clock positions to avoid fistula to the pubic symphysis in radiated patients and to the rectum in post-prostatectomy patients. For severe recurrent cases, injection of antifibrotic agents such as triamcinolone or mitomycin C may be used as an adjunct with good efficacy in selected patients. There remains some concern for serious adverse events associated with mitomycin C.⁴ In patients with the prostate in situ, transurethral prostatectomy or photovaporization of the prostate with GreenLight™, holmium or thulium laser may be indicated but carries a risk of pain, infection, necrosis and incontinence.

Figure 2. Lower urinary tract reconstruction for posterior urethral stenosis due to VUAS, BNC or prostatic obstruction and BMUS. BMG, buccal mucosal graft. EPA, excision and primary anastomosis.

Surgical Reconstruction

Surgical reconstruction is indicated for patients with PUS refractory to endoscopic therapy (fig. 2). For VUAS after radical prostatectomy, excision and reanastomosis can be performed via an abdominal, perineal or combined approach. Patency rates of 82% to 100% have been reported, although de novo incontinence is common.⁵ Our preference is a robotic transabdominal approach for its excellent visibility, reduced convalescence and preservation of the bulbar urethra for artificial sphincter placement if needed. Side-docking the da Vinci® Xi Surgical System allows for simultaneous perineal dissection if additional mobilization is needed.⁶

If the prostate is in situ and the obstruction is at the bladder neck, our preference is for a robotic transvesical approach with subtrigonal inlay of buccal mucosal graft.⁷ Other techniques such as YV-plasty, T-plasty and ventral graft inlay had success rates of 83% to 100% in small series.³

Once considered contraindicated, urethroplasty for post-radiation BMUS can achieve good results despite initial concerns regarding poor tissue vascularity. Our preferred approach is substitution urethroplasty with buccal mucosa, with a dorsal onlay technique shown to be safe and effective in 92% of cases.⁸ Other groups have reported 70% patency rates in patients with BMUS using a predominantly excision and primary anastomosis technique.⁹ A gracilis muscle flap may serve as a graft bed for a ventral onlay buccal mucosal graft in cases of long post-radiation BMUS with inadequate graft bed.¹⁰

Urinary Diversion

In rare cases lower urinary tract reconstruction is not feasible due to necrosis, dystrophic calcification or recurrent cancer. Options for the devastated posterior urethra are dependent on the feasibility of bladder preservation. Patients with a functional bladder but devasted outlet may be good candidates for catheterizable or incontinent channel creation. Patients with nonobliterative stricture disease and concern for persistent incontinence may also require bladder neck closure and possible augmentation.² Patients with severe pain, cancer, urosymphyseal fistula or impaired bladder capacity/compliance are best managed with cystectomy and urinary diversion.

Conclusion

Recalcitrant posterior urethral stenosis presents a significant challenge to the practicing urologist. Improvements in prostate cancer survivorship are likely to result in increased burden of disease in developed nations. While the mainstay of surgical intervention remains endoscopic, developments in surgical technique have broadened the treatment options and improved outcomes in men with recurrent obstruction.